# Chi documentation

Copyright (c) 2010, 2026 Contributors to the Eclipse Foundation
version v11.0

Chi is a modeling language for describing and analyzing performance of discrete event systems by means of simulation. It uses a process-based view, and uses synchronous point-to-point communication between processes. A process is written as an imperative program, with a syntax much inspired by the well-known Python language.

Chi is one of the tools of the Eclipse ESCET™ project. Visit the project website for downloads, installation instructions, source code, general tool usage information, information on how to contribute, and more.

| You can download this manual as a PDF as well. Or use the single-page HTML version.

Tutorial

  The Chi Tutorial teaches the Chi language, and its use in modeling and simulating systems to answer your performance questions.

  Some interesting topics are:

  - Basics (Data types, Statements, Modeling stochastic behavior)

  - Programming (Processes, Channels)

  - Modeling (Buffers, Servers with time, Conveyors)

Reference manual

  The Chi Reference Manual describes the Chi language in full detail, for example the top level language elements or all statements. It also contains a list with all standard library functions and a list with all distribution functions.

  Some interesting topics are:

  - Global definitions (Top level language elements)

  - Standard library functions (Standard library functions)

  - Distributions (Available distributions)

Tool manual

  The Tool manual describes the Chi simulator software. Use of the software to create and simulate Chi programs is also explained.

Release notes

  The Release notes provides information on all Chi releases.

Legal

  See Legal for copyright and licensing information.

A screenshot showing a Chi model and simulation with visualization: